51
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Morita Y, Callicott JH, Testa LR, Mighdoll MI, Dickinson D, Chen Q, Tao R, Lipska BK, Kolachana B, Law AJ, Ye T, Straub RE, Weinberger DR, Kleinman JE, Hyde TM. Characteristics of the cation cotransporter NKCC1 in human brain: alternate transcripts, expression in development, and potential relationships to brain function and schizophrenia. J Neurosci 2014; 34:4929-40. [PMID: 24695712 PMCID: PMC3972720 DOI: 10.1523/jneurosci.1423-13.2014] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 01/10/2014] [Accepted: 02/14/2014] [Indexed: 02/07/2023] Open
Abstract
Early in development, GABA, an inhibitory neurotransmitter in adults, is excitatory. NKCC1 (SLC12A2) encodes one of two cation chloride cotransporters mediating the conversion of GABA from excitatory to inhibitory. Using 3' and 5' RACE and PCR, we verified previously characterized alternative transcripts of NKCC1a (1-27) and NKCC1b (1-27(Δ21)), identified new NKCC1 transcripts, and explored their expression patterns during human prefrontal cortical development. A novel ultra-short transcript (1-2a) was expressed preferentially in the fetus. Expression of NKCC1b and 1-2a were decreased in schizophrenia compared with controls (NKCC1b: 0.8-fold decrease, p = 0.013; 1-2a: 0.8-fold decrease, p = 0.006). Furthermore, the expression of NKCC1b was associated with NKCC1 polymorphism rs3087889. The minor allele at rs3087889, associated with reduced NKCC1b expression (homozygous for major allele: N = 37; homozygous for minor allele: N = 15; 1.5-fold decrease; p < 0.01), was also associated with a modest increase in schizophrenia risk in a case-control sample (controls: N = 435; cases: N = 397, OR = 1.5). This same allele was then found associated with cognitive (n = 369) and fMRI (n = 313) intermediate phenotypes associated with schizophrenia-working memory (Cohen's d = 0.35), global cognition or g (d = 0.18), and prefrontal inefficiency (d = 0.36) as measured by BOLD fMRI during a working memory task. Together, these preclinical and clinical results suggest that variation in NKCC1 may increase risk for schizophrenia via alterations of mRNA expression at the molecular level and impairment of optimal prefrontal function at the macro or systems level.
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Affiliation(s)
- Yukitaka Morita
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Department of Psychiatry, Hiroshima City Hospital, Hiroshima City, Hiroshima Prefecture, 730-8518, Japan
| | - Joseph H. Callicott
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Lauren R. Testa
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Michelle I. Mighdoll
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
| | - Dwight Dickinson
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Qiang Chen
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
| | - Ran Tao
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
| | - Barbara K. Lipska
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Bhaskar Kolachana
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Amanda J. Law
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Neurodevelopmental and Neuropsychiatric Genetics Laboratory, Departments of Psychiatry and Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Tianzhang Ye
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
| | - Richard E. Straub
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
| | - Daniel R. Weinberger
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
- Departments of Psychiatry, Neurology, Neuroscience and the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Joel E. Kleinman
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
| | - Thomas M. Hyde
- Clinical Brain Disorders Branch, Genes, Cognition, and Psychosis Program, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, Maryland 21205
- Departments of Psychiatry, Neurology, Neuroscience and the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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Abstract
Seizures occur in approximately 1 to 5 per 1000 live births and are among the most common neurologic conditions managed by a neonatal neurocritical care service. There are several, age-specific factors that are particular to the developing brain, which influence excitability and seizure generation, response to medications, and impact of seizures on brain structure and function. Neonatal seizures are often associated with serious underlying brain injury such as hypoxia-ischemia, stroke, or hemorrhage. Conventional, prolonged, continuous video electroencephalogram is the gold standard for detecting seizures, whereas amplitude-integrated EEG is a convenient and useful bedside tool.
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Affiliation(s)
- Hannah C. Glass
- Departments of Neurology and Pediatrics University of California, San Francisco, United States of America
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Turner KL, Sontheimer H. Cl- and K+ channels and their role in primary brain tumour biology. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130095. [PMID: 24493743 DOI: 10.1098/rstb.2013.0095] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Profound cell volume changes occur in primary brain tumours as they proliferate, invade surrounding tissue or undergo apoptosis. These volume changes are regulated by the flux of Cl(-) and K(+) ions and concomitant movement of water across the membrane, making ion channels pivotal to tumour biology. We discuss which specific Cl(-) and K(+) channels are involved in defined aspects of glioma biology and how these channels are regulated. Cl(-) is accumulated to unusually high concentrations in gliomas by the activity of the NKCC1 transporter and serves as an osmolyte and energetic driving force for volume changes. Cell volume condensation is required as cells enter M phase of the cell cycle and this pre-mitotic condensation is caused by channel-mediated ion efflux. Similarly, Cl(-) and K(+) channels dynamically regulate volume in invading glioma cells allowing them to adjust to small extracellular brain spaces. Finally, cell condensation is a hallmark of apoptosis and requires the concerted activation of Cl(-) and Ca(2+)-activated K(+) channels. Given the frequency of mutation and high importance of ion channels in tumour biology, the opportunity exists to target them for treatment.
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Affiliation(s)
- Kathryn L Turner
- Department of Neurobiology and Center for Glial Biology in Medicine, University of Alabama at Birmingham, , 1719 6th Avenue South, CIRC 410, Birmingham, AL 35294, USA
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54
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What Is the Clinical Relevance of In Vitro Epileptiform Activity? ISSUES IN CLINICAL EPILEPTOLOGY: A VIEW FROM THE BENCH 2014; 813:25-41. [DOI: 10.1007/978-94-017-8914-1_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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55
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Blauwblomme T, Jiruska P, Huberfeld G. Mechanisms of ictogenesis. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 114:155-85. [PMID: 25078502 DOI: 10.1016/b978-0-12-418693-4.00007-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Epilepsy is a paroxysmal condition characterized by repeated transient seizures separated by longer interictal periods. Ictogenesis describes the processes of transition from the interictal state to a seizure. The processes include a preictal state, with specific clinical signs and a distinct electrophysiology which may provide opportunities to anticipate, or even prevent, seizures. Biological mechanisms of ictogenesis remain poorly understood and may vary between conditions/syndromes. We review here ictogenic processes including the involvement of pyramidal cells, interneurons and astrocytes, GABAergic and glutamatergic signaling, and ionic perturbations. Our review suggests that specific excitatory influences at the transition to an ictal event include (1) GABA receptor activation with a neuronal Cl(-) load and (2) a transient increase in external K(+).
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Affiliation(s)
- Thomas Blauwblomme
- Neurosurgery Unit, Hopital Necker-Enfants Malades, APHP, Paris, France; Université Paris Descartes, Paris, France; INSERM U1129-Infantile Epilepsies and Brain Plasticity, Paris, France; University Paris Descartes, PRES Sorbonne Paris Cité, Paris, France; CEA, Gif sur Yvette, France
| | - Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of Czech Republic, Prague, Czech Republic; Department of Neurology, 2nd Faculty of Medicine, Charles University in Prague, Motol University Hospital, Prague, Czech Republic
| | - Gilles Huberfeld
- INSERM U1129-Infantile Epilepsies and Brain Plasticity, Paris, France; University Paris Descartes, PRES Sorbonne Paris Cité, Paris, France; CEA, Gif sur Yvette, France; Clinical Neurophysiology Department, CHU Pitié-Salpêtrière, APHP, Paris, France; Université Pierre et Marie Curie, Paris, France.
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56
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Greenfield LJ. Molecular mechanisms of antiseizure drug activity at GABAA receptors. Seizure 2013; 22:589-600. [PMID: 23683707 PMCID: PMC3766376 DOI: 10.1016/j.seizure.2013.04.015] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/16/2013] [Accepted: 04/17/2013] [Indexed: 02/09/2023] Open
Abstract
The GABAA receptor (GABAAR) is a major target of antiseizure drugs (ASDs). A variety of agents that act at GABAARs s are used to terminate or prevent seizures. Many act at distinct receptor sites determined by the subunit composition of the holoreceptor. For the benzodiazepines, barbiturates, and loreclezole, actions at the GABAAR are the primary or only known mechanism of antiseizure action. For topiramate, felbamate, retigabine, losigamone and stiripentol, GABAAR modulation is one of several possible antiseizure mechanisms. Allopregnanolone, a progesterone metabolite that enhances GABAAR function, led to the development of ganaxolone. Other agents modulate GABAergic "tone" by regulating the synthesis, transport or breakdown of GABA. GABAAR efficacy is also affected by the transmembrane chloride gradient, which changes during development and in chronic epilepsy. This may provide an additional target for "GABAergic" ASDs. GABAAR subunit changes occur both acutely during status epilepticus and in chronic epilepsy, which alter both intrinsic GABAAR function and the response to GABAAR-acting ASDs. Manipulation of subunit expression patterns or novel ASDs targeting the altered receptors may provide a novel approach for seizure prevention.
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Affiliation(s)
- L John Greenfield
- Dept. of Neurology, University of Arkansas for Medical Sciences, 4301W. Markham St., Slot 500, Little Rock, AR 72205, United States.
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Rask-Andersen M, Masuram S, Fredriksson R, Schiöth HB. Solute carriers as drug targets: current use, clinical trials and prospective. Mol Aspects Med 2013; 34:702-10. [PMID: 23506903 DOI: 10.1016/j.mam.2012.07.015] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 05/28/2012] [Indexed: 11/18/2022]
Abstract
Solute carriers (SLCs) comprise a large family of membrane transporters responsible for the transmembrane transport of a wide variety of substrates such as inorganic ions, amino acids, neurotransmitters and sugars. Despite being the largest family of membrane transport proteins, SLCs have been relatively under-utilized as therapeutic drug targets by approved drugs. In this paper, we aim to catalogue therapeutic SLCs utilized by approved drugs or currently in clinical trials. By mining information on clinical trials from the Centerwatch.com "drugs in clinical trials database" we were able to identify potentially novel SLC drug targets currently under development. We also searched the literature for SLCs that have been discussed as future therapeutic drug targets. We find SLCs to be utilized as therapeutic targets in treatment of a wide variety of diseases and disorders, such as major depression, ADHD, osteoporosis and hypertension. Drugs targeting SLCs for treatment of diabetes, constipation and hypercholesterolaemia are currently in clinical trials. SLC drug targets have also been explored in clinical trials for cardioprotection after an ischemic event. SLCs are of particular interest as targets in antineoplastic treatment and for the targeted transport of cytotoxic drugs into tumors, e.g. via the glucose transporters GLUT1-5 and SGLT1-3.
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Affiliation(s)
- Mathias Rask-Andersen
- Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Uppsala SE 75124, Sweden.
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58
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Abstract
The treatment of neonatal seizures has not changed significantly over the last 50 years despite advances in antiepileptic drug (AED) development for older children and adults. Recently new drugs have emerged some of which address age-specific challenges or mechanisms and will be discussed in this review. The loop diuretic bumetanide blocks the neuronal NKCC1 co-transporter and is thought specifically to supress seizures in the immature brain. Levetiracetam has been used in children and infants with good efficacy, an excellent safety profile, and near-ideal pharmacokinetic characteristics. Randomised controlled trials are now underway to test the efficacy of some newer AEDs for neonatal seizures. Topiramate has been shown to have neuroprotective properties in addition to its antiepileptic action and trials in babies with hypoxic-ischaemic encephalopathy are now planned. There is an urgent need to develop age-specific AEDs for preterm and term babies. These drugs must be evaluated with multicentre, collaborative trials using innovative methods and high ethical standards to overcome age-specific challenges with the ultimate aim of improving the outcome for neonates with seizures.
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59
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Duarte ST, Armstrong J, Roche A, Ortez C, Pérez A, O'Callaghan MDM, Pereira A, Sanmartí F, Ormazábal A, Artuch R, Pineda M, García-Cazorla A. Abnormal expression of cerebrospinal fluid cation chloride cotransporters in patients with Rett syndrome. PLoS One 2013; 8:e68851. [PMID: 23894354 PMCID: PMC3716803 DOI: 10.1371/journal.pone.0068851] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 06/05/2013] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVE Rett Syndrome is a progressive neurodevelopmental disorder caused mainly by mutations in the gene encoding methyl-CpG-binding protein 2. The relevance of MeCP2 for GABAergic function was previously documented in animal models. In these models, animals show deficits in brain-derived neurotrophic factor, which is thought to contribute to the pathogenesis of this disease. Neuronal Cation Chloride Cotransporters (CCCs) play a key role in GABAergic neuronal maturation, and brain-derived neurotrophic factor is implicated in the regulation of CCCs expression during development. Our aim was to analyse the expression of two relevant CCCs, NKCC1 and KCC2, in the cerebrospinal fluid of Rett syndrome patients and compare it with a normal control group. METHODS The presence of bumetanide sensitive NKCC1 and KCC2 was analysed in cerebrospinal fluid samples from a control pediatric population (1 day to 14 years of life) and from Rett syndrome patients (2 to 19 years of life), by immunoblot analysis. RESULTS Both proteins were detected in the cerebrospinal fluid and their levels are higher in the early postnatal period. However, Rett syndrome patients showed significantly reduced levels of KCC2 and KCC2/NKCC1 ratio when compared to the control group. CONCLUSIONS Reduced KCC2/NKCC1 ratio in the cerebrospinal fluid of Rett Syndrome patients suggests a disturbed process of GABAergic neuronal maturation and open up a new therapeutic perspective.
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Affiliation(s)
- Sofia Temudo Duarte
- Department of Neurology, Hospital Sant Joan de Déu (HSJD), Barcelona, Spain.
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Khanna A, Walcott BP, Kahle KT. Limitations of Current GABA Agonists in Neonatal Seizures: Toward GABA Modulation Via the Targeting of Neuronal Cl(-) Transport. Front Neurol 2013; 4:78. [PMID: 23805124 PMCID: PMC3691543 DOI: 10.3389/fneur.2013.00078] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/09/2013] [Indexed: 01/18/2023] Open
Abstract
Neonatal intensive care has advanced rapidly in the last 40 years, with dramatic decreases in mortality and morbidity; however, for neonatal seizures, neither therapies nor outcomes have changed significantly. Basic and clinical studies indicate that seizures in neonates have long-term neurodevelopmental and psychiatric consequences, highlighting the need for novel pharmacotherapeutics. First-line treatments targeting GABAA receptors, like barbiturates and benzodiazepines, are limited in their efficacy and carry significant risks to the developing brain. Here, we review the use of current GABA agonist therapies for neonatal seizures and suggest other treatment strategies given recent developments in the understanding of disease pathogenesis. One promising avenue is the indirect manipulation of the GABAergic system, via the modulation of neuronal Cl− gradients, by targeting the cation-Cl− cotransporters (NKCC1 and KCC2) or their regulatory signaling molecules. This strategy might yield a novel class of more efficacious anti-epileptics with fewer side effects by specifically addressing disease pathophysiology. Moreover, this strategy may have ramifications for other adult seizure syndromes in which GABA receptor-mediated depolarizations play a pathogenic role, such as temporal lobe epilepsy.
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Affiliation(s)
- Arjun Khanna
- Division of Neurosurgery, Department of Surgery, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA
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Löscher W, Puskarjov M, Kaila K. Cation-chloride cotransporters NKCC1 and KCC2 as potential targets for novel antiepileptic and antiepileptogenic treatments. Neuropharmacology 2013; 69:62-74. [PMID: 22705273 DOI: 10.1016/j.neuropharm.2012.05.045] [Citation(s) in RCA: 200] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/22/2012] [Accepted: 05/28/2012] [Indexed: 12/31/2022]
Abstract
In cortical and hippocampal neurons, cation-chloride cotransporters (CCCs) control the reversal potential (EGABA) of GABAA receptor-mediated current and voltage responses and, consequently, they modulate the efficacy of GABAergic inhibition. Two members of the CCC family, KCC2 (the major neuron-specific K-Cl cotransporter; KCC isoform 2) and NKCC1 (the Na-K-2Cl cotransporter isoform 1 which is expressed in both neurons and glial cells) have attracted much interest in studies on GABAergic signaling under both normal and pathophysiological conditions, such as epilepsy. There is tentative evidence that loop diuretic compounds such as furosemide and bumetanide may have clinically relevant antiepileptic actions, especially when administered in combination with conventional GABA-mimetic drugs such as phenobarbital. Furosemide is a non-selective inhibitor of CCCs while at low concentrations bumetanide is selective for NKCCs. Search for novel antiepileptic drugs (AEDs) is highly motivated especially for the treatment of neonatal seizures which are often resistant to, or even aggravated by conventional AEDs. This review shows that the antiepileptic effects of loop diuretics described in the pertinent literature are based on widely heterogeneous mechanisms ranging from actions on both neuronal NKCC1 and KCC2 to modulation of the brain extracellular volume fraction. A promising strategy for the development of novel CCC-blocking AEDs is based on prodrugs that are activated following their passage across the blood-brain barrier. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Hannover, Germany.
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Pressler R, Auvin S. Comparison of Brain Maturation among Species: An Example in Translational Research Suggesting the Possible Use of Bumetanide in Newborn. Front Neurol 2013; 4:36. [PMID: 23596438 PMCID: PMC3625921 DOI: 10.3389/fneur.2013.00036] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 04/01/2013] [Indexed: 12/30/2022] Open
Affiliation(s)
- Ronit Pressler
- Institute of Child Health, University College London , London, UK ; Department of Clinical Neurophysiology, Great Ormond Street Hospital , London, UK
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63
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Maguire J, Salpekar JA. Stress, seizures, and hypothalamic-pituitary-adrenal axis targets for the treatment of epilepsy. Epilepsy Behav 2013; 26:352-62. [PMID: 23200771 PMCID: PMC3874873 DOI: 10.1016/j.yebeh.2012.09.040] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
Abstract
Epilepsy is a heterogeneous condition with varying etiologies including genetics, infection, trauma, vascular, neoplasms, and toxic exposures. The overlap of psychiatric comorbidity adds to the challenge of optimal treatment for people with epilepsy. Seizure episodes themselves may have varying triggers; however, for decades, stress has been commonly and consistently suspected to be a trigger for seizure events. This paper explores the relationship between stress and seizures and reviews clinical data as well as animal studies that increasingly corroborate the impact of stress hormones on neuronal excitability and seizure susceptibility. The basis for enthusiasm for targeting glucocorticoid receptors for the treatment of epilepsy and the mixed results of such treatment efforts are reviewed. In addition, this paper will highlight recent findings identifying a regulatory pathway controlling the body's physiological response to stress which represents a novel therapeutic target for modulation of the hypothalamic-pituitary-adrenal (HPA) axis. Thus, the HPA axis may have important clinical implications for seizure control and imply use of anticonvulsants that influence this neuronal pathway.
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Affiliation(s)
- Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, U.S.A
| | - Jay A. Salpekar
- Center for Neuroscience and Behavioral Medicine, Children’s National Medical Center, Washington, DC, U.S.A
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Cai X, Yang L, Zhou J, Zhu D, Guo Q, Chen Z, Chen S, Zhou L. Anomalous expression of chloride transporters in the sclerosed hippocampus of mesial temporal lobe epilepsy patients. Neural Regen Res 2013; 8:561-8. [PMID: 25206700 PMCID: PMC4146056 DOI: 10.3969/j.issn.1673-5374.2013.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 01/07/2013] [Indexed: 11/18/2022] Open
Abstract
The Na+-K+-Cl- cotransporter 1 and K+-Cl- cotransporter 2 regulate the levels of intracellular chloride in hippocampal cells. Impaired chloride transport by these proteins is thought to be involved in the pathophysiological mechanisms of mesial temporal lobe epilepsy. Imbalance in the relative expression of these two proteins can lead to a collapse of Cl- homeostasis, resulting in a loss of gamma-aminobutyric acid-ergic inhibition and even epileptiform discharges. In this study, we investigated the expression of Na+-K+-Cl- cotransporter 1 and K+-Cl- cotransporter 2 in the sclerosed hippocampus of patients with mesial temporal lobe epilepsy, using western blot analysis and immunohistochemistry. Compared with the histologically normal hippocampus, the sclerosed hippocampus showed increased Na+-K+-Cl- cotransporter 1 expression and decreased K+-Cl- cotransporter 2 expression, especially in CA2 and the dentate gyrus. The change was more prominent for the Na+-K+-Cl- cotransporter 1 than for the K+-Cl- cotransporter 2. These experimental findings indicate that the balance between intracellular and extracellular chloride may be disturbed in hippocampal sclerosis, contributing to the hyperexcitability underlying epileptic seizures. Changes in Na+-K+-Cl- cotransporter 1 expression seems to be the main contributor. Our study may shed new light on possible therapies for patients with mesial temporal lobe epilepsy with hippocampal sclerosis.
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Affiliation(s)
- Xiaodong Cai
- Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
| | - Libai Yang
- Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
| | - Jueqian Zhou
- Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
| | - Dan Zhu
- Department of Neurosurgery, Guangdong 999 Brain Hospital, Guangzhou 510510, Guangdong Province, China
| | - Qiang Guo
- Department of Neurosurgery, Guangdong 999 Brain Hospital, Guangzhou 510510, Guangdong Province, China
| | - Ziyi Chen
- Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
| | - Shuda Chen
- Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
| | - Liemin Zhou
- Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
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Eftekhari S, Mehvari Habibabadi J, Najafi Ziarani M, Hashemi Fesharaki SS, Gharakhani M, Mostafavi H, Joghataei MT, Beladimoghadam N, Rahimian E, Hadjighassem MR. Bumetanide reduces seizure frequency in patients with temporal lobe epilepsy. Epilepsia 2012; 54:e9-12. [DOI: 10.1111/j.1528-1167.2012.03654.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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66
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Aquaporins in drug discovery and pharmacotherapy. Mol Aspects Med 2012; 33:691-703. [DOI: 10.1016/j.mam.2012.01.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/13/2012] [Accepted: 01/15/2012] [Indexed: 11/18/2022]
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67
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Abstract
UNLABELLED The loop diuretics furosemide and bumetanide are commonly used in neonatal intensive care units (NICUs). Furosemide, because of its actions on the ubiquitous Na(+) -K(+) -2Cl(-) isoform cotransporter and its promotion of prostanoid production and release, also has non-diuretic effects on vascular smooth muscle, airways, the ductus arteriosus and theoretically the gastrointestinal tract. Loop diuretics also affect the central nervous system through modulation of the GABA-A chloride channel. CONCLUSION The loop diuretics have a variety of biological effects that are potentially harmful as well as beneficial. Care should be taken with the use of these agents because the range of their effects may be broader than the single action sought by the prescribing physician.
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Affiliation(s)
- Robert Cotton
- Department of Pediatrics, Division of Neonatology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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GABAergic excitation after febrile seizures induces ectopic granule cells and adult epilepsy. Nat Med 2012; 18:1271-8. [DOI: 10.1038/nm.2850] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 05/31/2012] [Indexed: 11/08/2022]
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Talos DM, Sun H, Kosaras B, Joseph A, Folkerth RD, Poduri A, Madsen JR, Black PM, Jensen FE. Altered inhibition in tuberous sclerosis and type IIb cortical dysplasia. Ann Neurol 2012; 71:539-51. [PMID: 22447678 PMCID: PMC3334406 DOI: 10.1002/ana.22696] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/17/2011] [Accepted: 12/09/2011] [Indexed: 12/31/2022]
Abstract
OBJECTIVE The most common neurological symptom of tuberous sclerosis complex (TSC) and focal cortical dysplasia (FCD) is early life refractory epilepsy. As previous studies have shown enhanced excitatory glutamatergic neurotransmission in TSC and FCD brains, we hypothesized that neurons associated with these lesions may also express altered γ-aminobutyric acid (GABA)(A) receptor (GABA(A)R)-mediated inhibition. METHODS Expression of the GABA(A)R subunits α1 and α4, and the Na(+)-K(+)-2Cl(-) (NKCC1) and the K(+)-Cl(-) (KCC2) transporters, in human TSC and FCD type II specimens were analyzed by Western blot and double label immunocytochemistry. GABA(A) R responses in dysplastic neurons from a single case of TSC were measured by perforated patch recording and compared to normal-appearing cortical neurons from a non-TSC epilepsy case. RESULTS TSC and FCD type IIb lesions demonstrated decreased expression of GABA(A)R α1, and increased NKCC1 and decreased KCC2 levels. In contrast, FCD type IIa lesions showed decreased α4, and increased expression of both NKCC1 and KCC2 transporters. Patch clamp recordings from dysplastic neurons in acute slices from TSC tubers demonstrated excitatory GABA(A)R responses that were significantly attenuated by the NKCC1 inhibitor bumetanide, in contrast to hyperpolarizing GABA(A)R-mediated currents in normal neurons from non-TSC cortical slices. INTERPRETATION Expression and function of GABA(A)Rs in TSC and FCD type IIb suggest the relative benzodiazepine insensitivity and more excitatory action of GABA compared to FCD type IIa. These factors may contribute to resistance of seizure activity to anticonvulsants that increase GABAergic function, and may justify add-on trials of the NKCC1 inhibitor bumetanide for the treatment of TSC and FCD type IIb-related epilepsy.
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Affiliation(s)
- Delia M. Talos
- Department of Neurology, Children’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | - Hongyu Sun
- Department of Neurology, Children’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | - Bela Kosaras
- Department of Neurology, Children’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | | | - Rebecca D. Folkerth
- Department of Pathology (Neuropathology), Children’s Hospital Boston
- Department of Pathology, Brigham and Women’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | - Annapurna Poduri
- Department of Neurology, Children’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | - Joseph R. Madsen
- Department of Neurosurgery, Children’s Hospital Boston
- Department of Neurosurgery, Brigham and Women’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | - Peter M. Black
- Department of Neurosurgery, Children’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
| | - Frances E. Jensen
- Department of Neurology, Children’s Hospital Boston
- Harvard Medical School, Boston, Massachusetts 02115
- Program in Neuroscience, Boston, Massachusetts 02115
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70
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Sebe JY, Baraban SC. The promise of an interneuron-based cell therapy for epilepsy. Dev Neurobiol 2011; 71:107-17. [PMID: 21154914 DOI: 10.1002/dneu.20813] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Of the nearly 3 million Americans diagnosed with epilepsy, approximately 30% are unresponsive to current medications. Recent data has shown that early postnatal transplantation of interneuronal precursor cells increases GABAergic inhibition in the host brain and dramatically suppresses seizure activity in epileptic mice. In this review, we will highlight findings from seizure-prone mice and humans that demonstrate the link between dysfunctional GABAergic inhibition and hyperexcitability. In particular, we will focus on rodent models of temporal lobe epilepsy, the most common and difficult to treat form of the disease, and interneuronopathies, an emerging classification. A wealth of literature showing a causal link between reduced GABA-mediated inhibition and seizures has directed our efforts to recover the loss of inhibition via transplantation of interneuronal precursors. Numerous related studies have explored the anticonvulsant potential of cell grafts derived from a variety of brain regions, yet the mechanism underlying the effect of such heterogeneous cell transplants is unknown. In discussing our recent findings and placing them in context with what is known about epilepsy, and how related transplant approaches have progressed, we hope to initiate a frank discussion of the best path toward the translation of this approach to patients with intractable forms of epilepsy.
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Affiliation(s)
- Joy Y Sebe
- Epilepsy Research Laboratory, Department of Neurological Surgery, University of California, San Francisco, California, USA.
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71
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Zhang ZJ, Valiante TA, Carlen PL. Transition to seizure: from "macro"- to "micro"-mysteries. Epilepsy Res 2011; 97:290-9. [PMID: 22075227 DOI: 10.1016/j.eplepsyres.2011.09.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 09/25/2011] [Accepted: 09/27/2011] [Indexed: 01/25/2023]
Abstract
One of the most terrifying aspects of epilepsy is the sudden and apparently unpredictable transition of the brain into the pathological state of an epileptic seizure. The pathophysiology of the transition to seizure still remains mysterious. Herein we review some of the key concepts and relevant literatures dealing with this enigmatic transitioning of brain states. At the "MACRO" level, electroencephalographic (EEG) recordings at time display preictal phenomena followed by pathological high-frequency oscillations at the seizure onset. Numerous seizure prediction algorithms predicated on identifying changes prior to seizure onset have met with little success, underscoring our lack of understanding of the dynamics of transition to seizure, amongst other inherent limitation. We then discuss the concept of synchronized hyperexcited oscillatory networks underlying seizure generation. We consider these networks as weakly coupled oscillators, a concept which forms the basis of some relevant mathematical modeling of seizure transitions. Next, the underlying "MICRO" processes involved in seizure generation are discussed. The depolarization of the GABA(A) chloride reversal potential is a major concept, facilitating epileptogenesis, particularly in immature brain. Also the balance of inhibitory and excitatory local neuronal networks plays an important role in the process of transitioning to seizure. Gap junctional communication, including that which occurs between glia, as well as ephaptic interactions are increasingly recognized as critical for seizure generation. In brief, this review examines the evidence regarding the characterization of the transition to seizure at both the "MACRO" and "MICRO" levels, trying to characterize this mysterious yet critical problem of the brain state transitioning into a seizure.
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Affiliation(s)
- Z J Zhang
- Division of Fundamental Neurobiology, Toronto Western Research Institute, Toronto Western Hospital, Toronto, ON, Canada.
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72
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Avoli M, de Curtis M. GABAergic synchronization in the limbic system and its role in the generation of epileptiform activity. Prog Neurobiol 2011; 95:104-32. [PMID: 21802488 PMCID: PMC4878907 DOI: 10.1016/j.pneurobio.2011.07.003] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 07/14/2011] [Accepted: 07/15/2011] [Indexed: 11/30/2022]
Abstract
GABA is the main inhibitory neurotransmitter in the adult forebrain, where it activates ionotropic type A and metabotropic type B receptors. Early studies have shown that GABA(A) receptor-mediated inhibition controls neuronal excitability and thus the occurrence of seizures. However, more complex, and at times unexpected, mechanisms of GABAergic signaling have been identified during epileptiform discharges over the last few years. Here, we will review experimental data that point at the paradoxical role played by GABA(A) receptor-mediated mechanisms in synchronizing neuronal networks, and in particular those of limbic structures such as the hippocampus, the entorhinal and perirhinal cortices, or the amygdala. After having summarized the fundamental characteristics of GABA(A) receptor-mediated mechanisms, we will analyze their role in the generation of network oscillations and their contribution to epileptiform synchronization. Whether and how GABA(A) receptors influence the interaction between limbic networks leading to ictogenesis will be also reviewed. Finally, we will consider the role of altered inhibition in the human epileptic brain along with the ability of GABA(A) receptor-mediated conductances to generate synchronous depolarizing events that may lead to ictogenesis in human epileptic disorders as well.
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Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery, and of Physiology, McGill University, Montreal H3A 2B4 Quebec, Canada.
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73
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Galanopoulou AS, Moshé SL. In search of epilepsy biomarkers in the immature brain: goals, challenges and strategies. Biomark Med 2011; 5:615-28. [PMID: 22003910 PMCID: PMC3227685 DOI: 10.2217/bmm.11.71] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Epilepsy and seizures are very common in the early years of life and are often associated with significant morbidity and mortality. Identification of biomarkers for the early detection of epileptogenicity, epileptogenesis, comorbidities, disease progression and treatment implementation will be very important in implementing more effective therapies. This article summarizes the current needs in the search for new early life epilepsy-related biomarkers and discusses the candidate biomarkers that are under investigation, as well as the challenges associated with the identification and validation of these biomarkers.
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Affiliation(s)
- Aristea S Galanopoulou
- Saul R Korey Department of Neurology, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Kennedy Center, Room 306, Bronx, NY 10461, USA.
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74
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Altered GABA signaling in early life epilepsies. Neural Plast 2011; 2011:527605. [PMID: 21826277 PMCID: PMC3150203 DOI: 10.1155/2011/527605] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 05/04/2011] [Accepted: 05/27/2011] [Indexed: 01/13/2023] Open
Abstract
The incidence of seizures is particularly high in the early ages of life. The immaturity of inhibitory systems, such as GABA, during normal brain development and its further dysregulation under pathological conditions that predispose to seizures have been speculated to play a major role in facilitating seizures. Seizures can further impair or disrupt GABAA signaling by reshuffling the subunit composition of its receptors or causing aberrant reappearance of depolarizing or hyperpolarizing GABAA receptor currents. Such effects may not result in epileptogenesis as frequently as they do in adults. Given the central role of GABAA signaling in brain function and development, perturbation of its physiological role may interfere with neuronal morphology, differentiation, and connectivity, manifesting as cognitive or neurodevelopmental deficits. The current GABAergic antiepileptic drugs, while often effective for adults, are not always capable of stopping seizures and preventing their sequelae in neonates. Recent studies have explored the therapeutic potential of chloride cotransporter inhibitors, such as bumetanide, as adjunctive therapies of neonatal seizures. However, more needs to be known so as to develop therapies capable of stopping seizures while preserving the age- and sex-appropriate development of the brain.
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75
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Roubertie A, Masson F, de Villepin-Touzery A, Suau B, Barbanel G, Rideau A, Cambonie G. Prise en charge des crises du nouveau-né. Arch Pediatr 2011; 18 Suppl 2:S56-64. [DOI: 10.1016/s0929-693x(11)71092-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kirmse K, Witte OW, Holthoff K. GABAergic depolarization during early cortical development and implications for anticonvulsive therapy in neonates. Epilepsia 2011; 52:1532-43. [PMID: 21668443 DOI: 10.1111/j.1528-1167.2011.03128.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Epileptic seizures rank among the most frequent neurologic symptoms during the neonatal period. Accumulating data from experimental animal studies and clinical trials in humans suggest that neonatal seizures could adversely affect normal brain development and result in long-term neurologic sequelae. Unfortunately, currently used anticonvulsive drugs are often ineffective in the neonatal period. One particularity of the immature neuronal network during neonatal development is that the neurotransmitter γ-aminobutyric acid (GABA) is mainly depolarizing, rather than hyperpolarizing as commonly observed in adults. This might, in part, explain not only the higher seizure propensity of the immature neuronal network, but also the limited anticonvulsive efficacy of GABA-enhancing drugs during early postnatal life. Accordingly, pharmacologic attenuation of GABAergic depolarization has been proposed as a strategy for neonatal seizure control. However, the underlying conjecture of a depolarizing mode of GABA action has been seriously challenged recently. In the present review, we will summarize the state of knowledge regarding GABAergic depolarization in early life and discuss how these data might impact a currently tested anticonvulsive strategy.
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Affiliation(s)
- Knut Kirmse
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany.
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77
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Nsimire Chabwine J, Vanden Eijnden S. A claim for caution in the use of promising bumetanide to treat neonatal seizures. J Child Neurol 2011; 26:657-8; author reply 658-9. [PMID: 21531912 DOI: 10.1177/0883073811401395] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
| | - Serge Vanden Eijnden
- Department of Neonatology, Erasmus Hospital Université Libre de Bruxelles, Belgium
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78
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Jayakumar AR, Valdes V, Norenberg MD. The Na-K-Cl cotransporter in the brain edema of acute liver failure. J Hepatol 2011; 54:272-8. [PMID: 21056502 DOI: 10.1016/j.jhep.2010.06.041] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/15/2010] [Accepted: 06/28/2010] [Indexed: 01/29/2023]
Abstract
BACKGROUND & AIMS Astrocyte swelling and brain edema associated with increased intracranial pressure are major complications of acute liver failure (ALF). The mechanism for such astrocyte swelling/brain edema, however, is not well understood. We recently found that ammonia, a key etiological factor in ALF, caused the activation of the Na-K-Cl cotransporter-1 (NKCC1) in cultured astrocytes, and that inhibition of such activation led to a reduction in astrocyte swelling, suggesting that NKCC1 activation may be an important factor in the mechanism of brain edema in ALF. To determine whether NKCC activation is also involved in brain edema in vivo, we examined whether NKCC activation occurs in the thioacetamide (TAA) rat model of ALF and determined whether treatment with the NKCC inhibitor bumetanide reduces the severity of brain edema in TAA-treated rats. METHODS Brain water content was measured using the gravimetric method. NKCC1 phosphorylation and protein expression were measured by Western blots. NKCC activity was measured in brain cortical slices. RESULTS NKCC activity was elevated in brain cortical slices of TAA-treated rats as compared to sham animals. Western blot analysis showed significant increases in total as well as phosphorylated (activated) NKCC1 protein expression in the cortical tissue. These findings were associated with a significant increase in brain water content which was attenuated by treatment with the NKCC inhibitor bumetanide. CONCLUSIONS Our studies suggest the involvement of NKCC in the development of brain edema in experimental ALF, and that targeting NKCC may represent a useful therapeutic strategy in humans with ALF.
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Affiliation(s)
- Arumugam R Jayakumar
- Department of Pathology, University of Miami, School of Medicine, Miami, FL 33101, USA
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79
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Kahle KT, Walcott BP, Staley KJ. Resolution of headache and papilledema in idiopathic intracranial hypertension associated with inhibition of Na+-K+-2Cl- cotransport. J Child Neurol 2011; 26:205-8. [PMID: 21285039 DOI: 10.1177/0883073810391264] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Medical treatment of idiopathic intracranial hypertension is often ineffective. Cerebrospinal fluid diversion or optic nerve sheath fenestration is employed when medical therapy fails. Here, we describe a case of a 13-year-old girl with idiopathic intracranial hypertension refractory to long-term trials of acetazolamide and furosemide at maximally tolerated doses. After declining surgical intervention despite progression of her visual symptoms, a trial of bumetanide (0.25 mg daily) monotherapy was successful in resolution of the patient's symptoms. These results suggest bumetanide could be effective in the treatment of idiopathic intracranial hypertension, perhaps by restoring the balance between cerebrospinal fluid formation and absorption and/or by altering the volume or ionic composition of the brain's extracellular fluid compartment.
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Affiliation(s)
- Kristopher T Kahle
- Department of Neurosurgery, Harvard Medical School and Massachusetts General Hospital, Boston, MA 02114, USA
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80
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Ichikawa J, Matsuki N, Koyama R. [Influences of febrile seizures on developing neuronal circuits: cellular and molecular approaches using animal models]. Nihon Yakurigaku Zasshi 2010; 136:219-24. [PMID: 20948158 DOI: 10.1254/fpj.136.219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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81
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Zawadzki L, Stafstrom CE. Status epilepticus treatment and outcome in children: what might the future hold? Semin Pediatr Neurol 2010; 17:201-5. [PMID: 20727491 DOI: 10.1016/j.spen.2010.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Status epilepticus is a life-threatening emergency that requires urgent treatment. Over the past decade, numerous advances have been made in the management of status epilepticus. Clinical studies have now established the benefit of early, aggressive treatment of status epilepticus with benzodiazepines in both prehospital and hospital settings. Neuroscientific advances are revealing mechanisms of status epilepticus that could translate into targets for treating acute status epilepticus and even reducing epileptogenesis. This article discusses future trends in the diagnosis, neurobiology, and treatment of status epilepticus.
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Affiliation(s)
- Lucyna Zawadzki
- Department of Neurology, Section of Pediatric Neurology, University of Wisconsin, Madison, WI 53705, USA
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82
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Abstract
PURPOSE OF REVIEW The aim is to review rational polytherapy of antiepileptic drugs in terms of conventional and novel mechanisms of action, consider combinations that might be beneficial when used as polytherapy, and discuss whether animal models can predict clinical efficacy. RECENT FINDINGS Many patients with epilepsy require concurrent treatment with more than one antiepileptic drug (rational polytherapy), but there is little information available as to which drugs might work best in combination. Conventional antiepileptic drugs act by blocking sodium channels or enhancing gamma-aminobutyric acid function. Some newer antiepileptic drugs have novel mechanisms of action, including impairment of the slow inactivation of sodium channels, binding to the presynaptic vesicle protein SV2A, binding to the calcium channel alpha2delta subunit, and opening select potassium channels. Several antiepileptic drugs have multiple or uncertain mechanisms of action. Quantitative techniques such as isobolography can be used to compare the efficacy and side effects of antiepileptic drug combinations in animals. However, neither such methods nor antiepileptic drug mechanisms of action have yet proven useful in predicting clinical benefit in patients. SUMMARY Animal models can be used to help predict drug combinations that might be effective clinically, based on novel mechanisms of action. However, at this point, antiepileptic drug choice in patients with epilepsy remains empirical.
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83
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Oxytocin is neuroprotective against oxygen–glucose deprivation and reoxygenation in immature hippocampal cultures. Neurosci Lett 2010; 477:15-8. [DOI: 10.1016/j.neulet.2010.04.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 04/08/2010] [Accepted: 04/10/2010] [Indexed: 12/12/2022]
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Current World Literature. Curr Opin Neurol 2010; 23:194-201. [DOI: 10.1097/wco.0b013e328338cade] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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85
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Vento M, de Vries LS, Alberola A, Blennow M, Steggerda S, Greisen G, Boronat N. Approach to seizures in the neonatal period: a European perspective. Acta Paediatr 2010; 99:497-501. [PMID: 20055774 DOI: 10.1111/j.1651-2227.2009.01659.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UNLABELLED In the neonatal period, seizures rank among the most common neurological symptoms, often indicating an underlying serious neurological condition. It is remarkable that although new tools have been incorporated into the diagnosis of neonatal seizures, there is no consensus about the therapeutic approach among different doctors and institutions. Hence, although phenobarbital is still considered the initial drug of choice, the protocols reported in the literature show a great variability in the approach to treatment of refractory seizures. We used a questionnaire to gain information regarding the treatment of seizures in the neonatal period in different European institutions. CONCLUSION We conclude that phenobarbital is still the initial drug of choice followed by benzodiazepines, except in preterm infants with a birth weight below 1800 g. In refractory seizures, the use of continuous lidocaine infusion is most common. Of note, clinical studies with newer drugs have been mostly performed in the United States but not in Europe.
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Affiliation(s)
- M Vento
- Division of Neonatology, University Hospital La Fe, Valencia, Spain.
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86
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Glaser N, Yuen N, Anderson SE, Tancredi DJ, O'Donnell ME. Cerebral metabolic alterations in rats with diabetic ketoacidosis: effects of treatment with insulin and intravenous fluids and effects of bumetanide. Diabetes 2010; 59:702-9. [PMID: 20028943 PMCID: PMC2828650 DOI: 10.2337/db09-0635] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Cerebral edema is a life-threatening complication of diabetic ketoacidosis (DKA) in children. Recent data suggest that cerebral hypoperfusion and activation of cerebral ion transporters may be involved, but data describing cerebral metabolic alterations during DKA are lacking. RESEARCH DESIGN AND METHODS We evaluated 50 juvenile rats with DKA and 21 normal control rats using proton and phosphorus magnetic resonance spectroscopy (MRS). MRS measured cerebral intracellular pH and ratios of metabolites including ATP/inorganic phosphate (Pi), phosphocreatine (PCr)/Pi, N-acetyl aspartate (NAA)/creatine (Cr), and lactate/Cr before and during DKA treatment. We determined the effects of treatment with insulin and intravenous saline with or without bumetanide, an inhibitor of Na-K-2Cl cotransport, using ANCOVA with a 2 x 2 factorial study design. RESULTS Cerebral intracellular pH was decreased during DKA compared with control (mean +/- SE difference -0.13 +/- 0.03; P < 0.001), and lactate/Cr was elevated (0.09 +/- 0.02; P < 0.001). DKA rats had lower ATP/Pi and NAA/Cr (-0.32 +/- 0.10, P = 0.003, and -0.14 +/- 0.04, P < 0.001, respectively) compared with controls, but PCr/Pi was not significantly decreased. During 2-h treatment with insulin/saline, ATP/Pi, PCr/Pi, and NAA/Cr declined significantly despite an increase in intracellular pH. Bumetanide treatment increased ATP/Pi and PCr/Pi and ameliorated the declines in these values with insulin/saline treatment. CONCLUSIONS These data demonstrate that cerebral metabolism is significantly compromised during DKA and that further deterioration occurs during early DKA treatment--consistent with possible effects of cerebral hypoperfusion and reperfusion injury. Treatment with bumetanide may help diminish the adverse effects of initial treatment with insulin/saline.
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Affiliation(s)
- Nicole Glaser
- Department of Pediatrics, University of California, Davis, California, USA.
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89
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Glykys J, Dzhala VI, Kuchibhotla KV, Feng G, Kuner T, Augustine G, Bacskai BJ, Staley KJ. Differences in cortical versus subcortical GABAergic signaling: a candidate mechanism of electroclinical uncoupling of neonatal seizures. Neuron 2009; 63:657-72. [PMID: 19755108 DOI: 10.1016/j.neuron.2009.08.022] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 08/19/2009] [Accepted: 08/19/2009] [Indexed: 01/24/2023]
Abstract
Electroclinical uncoupling of neonatal seizures refers to electrographic seizure activity that is not clinically manifest. Uncoupling increases after treatment with Phenobarbital, which enhances the GABA(A) receptor (GABA(A)R) conductance. The effects of GABA(A)R activation depend on the intracellular Cl(-) concentration ([Cl(-)](i)) that is determined by the inward Cl(-) transporter NKCC1 and the outward Cl(-) transporter KCC2. Differential maturation of Cl(-) transport observed in cortical versus subcortical regions should alter the efficacy of GABA-mediated inhibition. In perinatal rat pups, most thalamic neurons maintained low [Cl(-)](i) and were inhibited by GABA. Phenobarbital suppressed thalamic seizure activity. Most neocortical neurons maintained higher [Cl(-)](i), and were excited by GABA(A)R activation. Phenobarbital had insignificant anticonvulsant responses in the neocortex until NKCC1 was blocked. Regional differences in the ontogeny of Cl(-) transport may thus explain why seizure activity in the cortex is not suppressed by anticonvulsants that block the transmission of seizure activity through subcortical networks.
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Affiliation(s)
- Joseph Glykys
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02144, USA
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90
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Kahle KT, Simard JM, Staley KJ, Nahed BV, Jones PS, Sun D. Molecular mechanisms of ischemic cerebral edema: role of electroneutral ion transport. Physiology (Bethesda) 2009; 24:257-65. [PMID: 19675357 DOI: 10.1152/physiol.00015.2009] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The brain achieves homeostasis of its intracellular and extracellular fluids by precisely regulating the transport of solute and water across its major cellular barriers: endothelia of the blood-brain barrier (BBB), choroid plexus epithelia, and neuroglial cell membranes. Cerebral edema, the pathological accumulation of fluid in the brain's intracellular and extracellular spaces, is a major cause of morbidity and mortality following stroke and other forms of ischemic brain injury. Until recently, mechanisms of cerebral edema formation have been obscure; consequently, its treatment has been empiric and suboptimal. Here, we provide a paradigm for understanding ischemic cerebral edema, showing that its molecular pathogenesis is a complex yet step-wise process that results largely from impaired astrocytic cell volume regulation and permeability alterations in the cerebral microvasculature, both of which arise from pathological changes in the activities of specific ion channels and transporters. Recent data has implicated the bumetanide-sensitive NKCC1, an electroneutral cotransporter expressed in astrocytes and the BBB, in cerebral edema formation in several different rodent models of stroke. Pharmacological inhibition or genetic deficiency of NKCC1 decreases ischemia-induced cell swelling, BBB breakdown, cerebral edema, and neurotoxicity. Combination pharmacological strategies that include NKCC1 as a target might thus prove beneficial for the treatment of ischemic, and potentially other types of, cerebral edema.
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Affiliation(s)
- Kristopher T Kahle
- Departments of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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